Timing of meroplankton occurrence in high-Arctic fjords with different primary productive regimes Eike Stübner & Janne E. Søreide The University Centre on Svalbard & University in Tromsø Why meroplankton? • Indication of periodical high important in coastal areas also in Arctic areas • common feature? • => importance in the food web? • Seasonality still not well enough understood in Arctic Seas =>Meroplankton exhibit strong seasonality Presented study: • Hypothesis: Abundance peaks of meroplankton are correlated to the occurrence of the spring bloom. => delayed in areas with delayed spring bloom • Additional questions: How much does this group contribute to the zooplankton community? Can we capture main pattern observed in high resolution time series in coarser time series studies as well? Methods: • Time series: 3 different fjords: • High Arctic localities • Sea ice – no sea ice similar latitude, • Sea ice cover different latitudes • Resolution • 1x high resolution (bi-weekly) • 2x good resolution (~monthly) • Data from several projects and years • ArcWin, Cleopatra I & II (UNIS, UiT, IOPAS) => RiF + BAB • MeroSeason I & II, UniPlankton, MicroFun (UNIS, IOPAS) => IsA Methods • Fine mesh size: 63 µm WPII • => Small sized organisms • Several depth layers • Exclusion of some groups in analysis • Background data • CTD/mooring => Temperature, salinity, fluorescence • Chlorophyll a • Day-length (sun over horizon) Rijpfjorden - 2007 Billefjorden - 2013 from Søreide et. al 2010 Adventfjorden – 2012/13 Rijpfjorden - 2007 Difference in timing Billefjorden - 2013 from Søreide et. al 2010 Adventfjorden – 2012/13 Timing and bloom Timing and bloom Timing and bloom Gastropoda Echinodermata Bivalvia Cirripedia Polychaeta Timing and bloom Gastropoda Echinodermata Bivalvia Cirripedia Polychaeta Adventfjorden High resolution => several peaks apparent 2013 2012 Summary • Main meroplankton peak follows the phytoplankton bloom • Bivalvia dominate in the meroplankton fraction • Cirripedia also very important, but in Rijpfjorden Echinodermata • High resolution time series shows several peaks Conclusion: • Hypothesis: Abundance peaks of meroplankton are correlated to the occurrence of the spring bloom. • Questions: Periodical importance common feature? How much does this group contribute to the zooplankton community? Can we capture main pattern observed in high resolution time series in coarser time series studies as well? Conclusion: • Hypothesis: Abundance peaks of meroplankton are correlated to the occurrence of the spring bloom. • Questions: Periodical importance common feature? How much does this group contribute to the zooplankton community? Can we capture main pattern observed in high resolution time series in coarser time series studies as well? Conclusion: • Hypothesis: Abundance peaks of meroplankton are correlated to the occurrence of the spring bloom. • Questions: Periodical importance common feature? How much does this group contribute to the zooplankton community? Can we capture main pattern observed in high resolution time series in coarser time series studies as well? Conclusion: • Hypothesis: Abundance peaks of meroplankton are correlated to the occurrence of the spring bloom. • Questions: Periodical importance common feature? How much does this group contribute to the zooplankton community? Can we capture main pattern observed in high resolution time series in coarser time series studies as well? Thank you for your attention!! • Acknowledgement: • Data access: • Cleopatra I & II • ArcWin • Adventfjorden field campaign • MicroFun • Identification • IOPAS http://www.mare-incognitum.no/ http://www.unis.no/20_RESEARCH/2020_Arctic_Biology/AFC.htm.